An implanted biomaterial with well-controlled architecture can elicit beneficial biological responses. In particular, biomaterials with interconnecting pores are known to promote neovascularization and angiogenesis within the pores. For instance, porous biomaterials with pore size large enough to allow macrophage penetration result in increased vascularity in the capsule tissue. Brauker J. H. et al., J Biomed Mater Res 29, 1517 (1995). Increased vascularity was also shown to correlate with improved diffusion and plasma-exchange properties. Sharkaway A. A. et al., J Biomed Mater Res 40, 586 (1998). Certain pore sizes were recognized as allowing an increased colonization of host macrophages within the pore structure and maximizing the density of new vessels within the porous material. These proangiogenic characteristics of the porous biomaterials make them particularly useful as scaffolds for stimulating tissue growth and promoting wound healing.
Known porous biomaterials typically allow tissue ingrowth in an implant to a depth of approximately 0.2 mm to about 1 mm from the surface of the implant. This limitation of the extent of vascularization is due, at least in part, to mechanical constraints on the size of blood vessels that can develop via angiogenesis in and through the interconnected porous structure. Thus, there is a need for developing biomaterials that allow extensive tissue ingrowth.